JPH02210629A - Optical disk and production thereof - Google Patents

Abstract

PURPOSE:To form a reproduced disk plate in a short period of time and to reduce the cost thereof by converting the phase change film of a rewriting type phase change optical disk exclusive of either of the film part corresponding to the record 1 or 0 of the above-mentioned film to a ROM type optical disk, thereby forming the ROM type phase change optical disk. CONSTITUTION:A crystal film (II) 72 of an InSb layer change film is formed as a recording film on a quartz substrate 31 of the ROM type optical disk. The crystal film (I) 71 corresponding to the record 0 of the InSb layer change film is removed from this crystal film 72 and the crystal film (II) 72 correspond ing to the record 1 is made to remain. The phase change optical disk provided with the phase change film is irradiated with laser light, by which the crystal film (I) 71 state is reversibly changed to the crystal film (II) 72 state and the crystal film (II) 72 is converted to a simple cubic crystal. The crystal film (II) 72 is obtd. by rapid heating and rapid cooling. The original substrate is used as the ROM type optical disk and the master disk is produced form the sufficiently debugged original substrate and, therefore, errors are eliminated. The manhours for the processing are decreased by integral transfer and the cost of the optical disk is reduced.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a read-only (ROM) optical disk and its manufacturing method, with the aim of manufacturing a duplicate optical disk at low cost and quickly after receiving an order. Membrane record “
An optical disc converted to a ROM type optical disc is constructed by removing either one of the film portions corresponding to l'' or 0°.

In addition, using the converted ROM type optical disk as a source substrate, a master disk is prepared by closely exposing the source substrate to form a pit pattern made of a photoresist film, and using the master disk, an R.
The present invention is characterized by a method for manufacturing an optical disc, in which an OM type duplicate optical disc plate is formed.

[Industrial application field]

The present invention relates to an optical disc and a method of manufacturing the same, and particularly to a read-only (ROM) optical disc and a method of manufacturing the same.

Optical discs have a larger recording capacity than other recording media.
Optical disks have many advantages such as non-contact recording and playback and long life, and a wide variety of products are rapidly being developed and mass-produced, but such optical disks require significant cost reduction. There is.

[Conventional technology]

Optical discs include read-only (ROM) types, write-once types, and rewritable types, but all of them have a large number of tracks on the disc, and countless pits are written on each track. It is configured to read out. Figure 4 shows CD (compact disc)-R among the optical discs.
A partial cross-sectional view of the OM is shown, for example, a diameter of 130 m.
m, thickness 1.2ra11 polycarbonate substrate 1 to 1
．． Numerous pits 2 (this pit corresponds to a record "lo" or "0") are formed spirally at a pitch P of 6 μm, and the presence or absence of the pit corresponds to a record of "1" or "0". The pits are read by an optical head 6 through an objective lens 5 from the back surface of the substrate, and an aluminum (AI) reflective film 3 is deposited on the top surface of the pit, and a protective film 4 is coated on top of the aluminum (AI) reflective film 3.

Although FIG. 4 is a schematic partial cross-sectional view of a CD-ROM, the present invention will be explained below using similar schematic cross-sectional views.

FIGS. 5(a) to 5(f) show step-by-step cross-sectional views of a conventional CD-ROM manufacturing method. Referring to FIG. 5(a), a photoresist film 1 is formed on a glass substrate 11.
2 (thickness: 1000), and exposed by irradiating laser light from above. At this time, an optical modulator such as an optical path changing element or a light amount modulator is placed in the optical path of the laser beam, and the optical modulator is controlled by an external signal to perform exposure 0N10FF, thereby allowing partial exposure.

Refer to FIG. 5(b); next, this is developed by a wet development method to form pits in the photoresist film 12. That is, if the photoresist film 2 is of positive type, pits are formed because the exposed portions are developed and removed. This becomes the master disc with a built-in recording pit.

Refer to FIG. 5C; next, a nickel plating film 13 having a thickness of ffIII+ is formed thereon by a plating method.

See FIG. 5(d); then, by removing the glass substrate 11 and the photoresist film 12, only the nickel plating film 13 provided with the recording pins can be taken out.

This is the mold (stamper) for the optical disc.

Refer to FIG. 5(e); Next, a mold made of this nickel plating film 13 is attached to a mold 14, and a polycarbonate substrate 1 is injection molded by an injection molding method.

Refer to FIG. 5(f): Then, a polycarbonate substrate (2) with the pits transferred thereto is formed, which is a duplicate optical disk plate.

Refer to FIG. 5(6); Next, as described above, the aluminum reflective film 3 is deposited on the polycarbonate substrate 1, and the protective film 4 is further coated to complete the CD-ROM.

On the other hand, phase change optical discs are among the rewritable optical discs that have been intensively studied recently, and they are shown in Figs.
It is shown in C). FIG. 6(a) is a perspective cross-sectional view of a phase change optical disk, FIG. 6(b) is an enlarged view of the 0 part in FIG. 6(a), and FIG. , symbol l in the figure is a polycarbonate substrate, 7 is an InSb (indium antimony) phase change film, and 71 is a crystal film 1 of them.
．． 72 is a portion of the crystal film (recording film).

In this example, the phase change type optical disk has an InSb phase change film 7.
This is a rewritable optical disc in which crystal film I state ← → crystal film ■ state is reversibly changed by laser beam irradiation. ” will be a pit corresponding to either of these. Such a phase change optical disk also uses 5bTeS as a phase change film.
There are materials such as e, In5eTe, and Ge5eTe, which can be reversibly changed from an amorphous state to a crystalline state by irradiation with laser light.

[Problem to be solved by the invention]

By the way, such optical disks contain a large number of pits, for example, pits with a storage capacity of about 500 MB, and in the CD-ROM type optical disk for copying described above, the master disk described in FIG. 5 (5) is magnetically Since depacking is performed using tape or the like, there is a drawback that a large number of processing steps are required, which increases costs. In addition, it may happen that the depacking is not done completely and some defective parts still remain, and if the mold has already been made at that time, there will be a big loss and it will become even more expensive, and sometimes several molds will be required. The cost may be as high as 1 million yen, and in that case, the cost will be added to the cost of the duplicate optical disk, further increasing the cost.

The present invention makes such a duplicate optical disc plate inexpensive and
This paper proposes an optical disc and its manufacturing method that aims to shorten the manufacturing period by quickly manufacturing the disc after receiving an order.

[Means to solve the problem]

The task was to remove either one of the phase change film portions corresponding to recording degrees 1' or '0' in a rewritable phase change optical disc to create a ROM type phase change optical disc that was converted into a ROM type optical disc. Using the converted ROM type optical disk as a source substrate, a master disk is prepared by closely exposing the source substrate to form a pit pattern made of a photoresist film, and a ROM type duplicate optical disk plate is formed from the master disk. The problem is solved by the manufacturing method.

[For production]

That is, the present invention can be applied to the conventional rewritable optical disc i.
The disc is converted into a ROM type optical disc, and using this as a base substrate, a master disc is produced by batch transfer exposure.

A large number of duplicate optical disk plates are manufactured from the original disk, and in this way, the original substrate can be used as a ROM-type optical disk, and there is no need to separately manufacture the master disk of the duplicate optical disk disk, There is no error since the master disc is produced from the original substrate which has already been sufficiently depacked, and furthermore, the number of processing steps is significantly reduced because of the -batch transfer exposure, and the cost of the optical disc to be duplicated can be significantly reduced.

〔Example〕

Examples will be described in detail below with reference to the drawings.

FIGS. 1(a) to (C) are diagrams showing a ROM type optical disk according to the present invention, in which FIG. 1(a) is a perspective sectional view like FIG. 6, and FIG. 1(b) is a ) is an enlarged view of the 0 portion of FIG. 1(C), which shows the BB cross section of FIG. 1(b). Symbol 31 in the figure is a quartz substrate (quartz substrate with good flatness), 72
is a crystal film (recording film) of an InSb phase change film. This figure shows a portion of the InSb phase change film 7 of the phase change optical disc shown in FIG. )
This is the configuration of a ROM-type optical disc that retains the following information.

By the way, in the phase change optical disk provided with this InSb phase change film 7, it is possible to reversibly change the crystal film 1 state←→crystal film ■ state by irradiation with laser light.
The crystal film I is a zinc sulfide type crystal, and the crystal film ■ is a metastable film of a simple cubic crystal.This crystal film ■ can be rapidly heated and cooled to obtain the crystal film ■ state, and when the crystal film I is slowly cooled, the crystal film ■ state can be obtained. Can be formed. In addition, the crystal film I is easily etched by plasma gas, and the crystal film I and the crystal film II have a property that their etching rates are different.

The present invention utilizes this difference in etching rate to
The rewritable optical disk shown in the figure is converted into a ROM type optical disk, and FIG. 2 shows a cross-sectional view of the process during formation. To explain the fabrication outline, the rewritable phase change optical disk shown in Fig. 6 is loaded into a sputtering device, the phase change optical disk and the electrodes are placed facing each other, the device is evacuated to a high vacuum, and then argon gas is introduced into the device. A high voltage is applied between the electrode and the optical disk with a reduced pressure of 1 Torr to several Torr. Then, the argon gas is turned into plasma and collides with the InSb phase change film 7. Then,
Since the crystal film (2) is easily etched, it is removed, leaving only the crystal film (2) (recording film part), and in this way the ROM type optical disk shown in FIG. 1 can be manufactured.

This ROM type optical disk can be used as is, but it can also be used as a base substrate to produce a master for a duplicate optical disk.

Next, FIGS. 3(a) to 3(d) show the CD-ROM according to the present invention.
It shows a step-by-step cross-sectional view of a ROM manufacturing method, and will be explained step by step.

Refer to FIG. 3(a); a glass substrate 21 coated with a positive photoresist film 22 (thickness: 1,000 yen) is placed, and the original substrate consisting of the ROM type optical disk shown in FIG. 1 is turned over on top of the glass substrate 21. The recording film (crystal film 3) 72 portion is brought into close contact with the photoresist film 22, and the quartz substrate 31 is exposed all at once from the back surface. For this exposure, it is desirable to use an exposure method that uses far ultraviolet rays or X-rays, which is suitable for fine exposure.In this case, the portion of the photoresist film 22 that is in close contact with the remaining recording film portion 72 will be left unexposed, and the other portions will be exposed. .

(See FIG. 3); Next, when this is developed, the exposed portion of the positive photoresist film 22 is removed, and the unexposed portion remains, and the master disk on which the focus pattern made of the photoresist film 22 is formed is formed. It can be made.

Refer to FIG. 3(C); next, a nickel plating film 23 having a thickness of lll11 units is deposited thereon by a plating method.

Refer to FIG. 3(d); next, the glass substrate 21 and the photoresist film 22 are removed, and only the nickel plating film 23 provided with the recording bits is taken out. This is the mold for the optical disc.

Although not shown hereafter, the conventional method described above is shown in Fig. 5 (e).
) to (g), a mold made of nickel plating film 23 is attached to the mold, and a polycarbonate substrate 1 is molded by the injection molding method, and this is a duplicate optical disk plate. reflective film.

A protective film is applied and a CD-ROM is prepared.

If a CD-ROM is manufactured in this way, there will be no error since the master disc is manufactured from a sufficiently depacked original substrate, and the number of processing steps will be extremely reduced since the master disc is manufactured using the -batch transfer exposure method. .

Although this example is a manufacturing method for duplicating a CD-ROM, this manufacturing method can also be applied to duplicating other ROM type optical discs. In addition to the quartz substrate, polycarbonate 1-. Although a transparent plate such as PMMA is used, it can also be applied to those substrates.

Further, although the above embodiment has been described as an example in which the phase change film 7 is not coated with a protective film, there is no problem even if a selectively removable protective film is coated.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to convert a rewritable phase change optical disc into a ROM type optical disc, which was previously impossible, and furthermore, it is possible to convert a rewritable phase change optical disc into a ROM type optical disc, which was previously impossible. It is possible to make a large number of copies of ROM-type optical discs such as CD-ROMs, there is no need to spend many man-hours to create master discs separately, there is no error because master discs are created from the original board that has already been sufficiently depacked, and, - Because it is a batch transfer exposure, the number of processing steps is greatly reduced, and the cost of optical disks can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a ROM-type optical disk according to the present invention, FIG. 2 is a cross-sectional view of the ROM-type optical disk according to the present invention in the middle of a process, and FIG. FIG. 4 is a partial cross-sectional view of a CD-ROM, and FIG. 5 is a cross-sectional view of a conventional CD-ROM manufacturing method in the order of steps. FIG. 6 is a diagram showing a conventional phase change optical disk. In the figure, 1 is a quartz polycarbonate substrate, 2 is a bit, 3 is an aluminum reflective film, 4
is a protective film, 5 is an objective lens, 6 is an optical head, 7 is a TnSb phase change film, 11 and 21 are glass substrates, 12.22 is a photoresist film, 13 and 23 are nickel plated films, 31 is a quartz substrate, 71 is a Crystal film I, 72 indicates crystal film ■. W.F. Shito day ear 1- or 7P3ROM bird r grass de) 77 bundle n
Figure 1 CD-ROM rl 忰KE u CIn Figure 4 Figure 8th CD-BOMiqMit;
g・y* #frr mFig.

Claims (2)

[Claims] (1) An optical disc characterized in that a rewritable phase change optical disc is converted into a ROM type optical disc by removing the film portion of one of the phase change films corresponding to recording '1' or '0'. (2) Using a ROM-type optical disk converted by removing one film portion corresponding to recording '1' or '0' of the phase change film in a rewritable phase change optical disk as a source substrate, the source substrate is closely exposed to photoresist. 1. A method for manufacturing an optical disc, comprising: producing a master disc on which a pit pattern made of a film is formed; and using the master disc to form a ROM type duplicate optical disc plate.